The present invention pertains to surgical cutters and more particularly pertains to disposable surgical cutters such as acetabular reamer cups and patella cutters.
Acetabular reamers are surgical tools, which are used to cut hemispherical cavities in pelvis bones for the insertion of artificial hip joints. An acetabular reamer is composed of an acetabular reamer cup mounted on a tool driver, which in turn is mounted in the chuck or collet of a portable drill or flexible powered shaft. Acetabular reamer cups have a complex arrangement of precisely shaped cutting surfaces extending outwardly from an essentially hemispherical shell. Acetabular reamer cups are separable from their tool drivers for changing cup size prior to or during surgery, cleaning, and/or sharpening.
Acetabular reamers must be capable of producing cavities with very close tolerances. Both acetabular reamers and patella cutters must also minimize any risk of causing contamination and be light in weight and fit on an appropriate tool driver with a minimum of free play quickly and easily without tools. Prior acetabular reamer cups and patella cutters must be cleaned after each use. Thus, the desirability of a disposable reamer cup and cutter.
Some previous acetabular reamers have used an openbottom acetabular reamer cup gripped by the tool driver by means of a flange and slot and an opposed springloaded ball catch, like that on a socket wrench or socket driver. This presents a problem in that the catch tends to trap dried blood, which is very difficult to remove during cleaning. An additional problem is that unless tolerances of cups and tool drivers are made very close, at great cost, there is considerable free play between a cup and its tool driver. This increases wear and decreases the precision of the tool.
An alternative acetabular reamer, described in U.S. Pat. No. 4,811,632, utilizes a convex-bottomed acetabular reamer cup having a large central opening complementary in shape to a flange on the tool driver. Since the tool driver also grips the cup with a clamping action, extremely close tolerances are not required to prevent free play between the cup and driver. The convex bottom of the cup eliminates any internal ninety degree angles which could catch contaminants and the large central opening permits easy cleaning. The acetabular reamer cup is, however, complex in shape and expensive and, like all acetabular reamer cups, difficult to resharpen and must be cleaned between uses.
Patella cutters are surgical tools, similar in some respects to acetabular reamer cups, which are used to cut or shaped the under side of the patella or knee cap as desired. A patella cutting system is generally composed of a cutter mounted on a tool driver, which in turn is mounted in the chuck or collet of a portable drill or flexible powered shaft. Cutters for patella have a complex arrangement of precisely shaped cutting edges extending outwardly from a flat planer surface. Cutters are separable from their tool drivers for changing cutter size prior to or during surgery, cleaning, and/or sharpening.
Unique to knee surgery and some hip operations is the utilization of milled bone, tissue and debris as filler to be placed between the artificial insert and the body to assist the healing process. Thus, prior patella cutting systems provide a hollow, opaque interior cavity for retaining bone debris, like that described in allowed U.S. patent application Ser. No. 07/851,504 filed on Mar. 16, 1992, entitled Patella Cutting System. The cutters described therein, however, are suited for use only in conjunction with the accompanying tool driver also described therein and each is composed of high-grade steel. This presents a problem in that the cutting lids cannot be rotatably driven by a number of different tool drivers and the cost of manufacturing the matching tool drivers and cutting lids is unnecessarily excessive. Also, with the tool drivers disclosed, the operator cannot usually see the accumulation of bone debris through the back of the driver as is desired.
It is therefore highly desirable to provide an improved acetabular reamer cup and patella cutter.
It is also highly desirable to provide an improved acetabular reamer cup and patella cutter which are disposable and fit on a tool driver with a minimum of free play.
It is also highly desirable to provide an improved acetabular reamer cup and patella cutter which are disposable and precise in size, light in weight and inexpensive.
It is also highly desirable to provide an improved acetabular reamer cup and patella cutter which are disposable and quick and easy to install and remove from a tool driver without tools.
It is finally highly desirable to provide an improved acetabular reamer cup and patella cutter which meet all of the above desired features.